Relevance of PSInSAR Analyses at ITRF Co-location Sites
Résumé
Abstract The PSInSAR (Persistent Scatterer Interferometric Synthetic Aperture Radar) technique allows determining deformation maps over large areas. In this paper, we investigate the applicability of PSInSAR analyses for ITRF co-location sites characterized by spatial extents varying between 20 m and 3 km. Although PSInSAR shows some limitations such as spatial resolution and sparse Persistent Scatterer distribution, this technology can be used to determine relative motion between geodetic instrumentation at sufficient spatial detail, specifically for large sites. The spatial resolution varies from 3 × 22 m [rg × az] from typical Sentinel 1A/1B products (IW mode) to 0.6 × 0.25 m [rg × az] for staring spotlight mode of TerraSAR-X/Tandem-X. As an illustration, C-band PSInSAR results derived by the European Ground Motion Service (EGMS) from Sentinel 1A/1B images have been investigated for the five largest ITRF co-location sites in Europe. Maximum relative velocity differences have been found to be smaller than 2.0 mm/yr. Moreover, as high-resolution X-band SAR images show great potential for mapping deformations at high resolution, an inventory of already available TerraSAR-X/Tandem-X images at ITRF co-location sites has been established. Based on this, five candidate sites are proposed for further PSInSAR analyses using X-band data.